1. Field of the Invention
The present invention relates to a nailing machine, in which connected nails are successively fed into an ejecting portion and the nail supplied into the ejecting portion is hammered by utilizing the power of compressed air after breaking the nail-to-nail connected condition. More specifically, the present invention relates to a nailing machine for both types of connected nails including the nails connected together by a metal wire and the nails connected by plastic sheets that are respectively formed into holding leaves by holding down both sides of the plastic sheets in order to hold and connect the nails.
2. Description of the Related Art
As connected nails for use in nailing machines driven by compressed air, there are known types of connected nails including wire-connected nails prepared by welding (fusion-bonding) a metal wire to nail shanks for the connecting purpose and nails connected by a plastic sheet prepared by forming a pair of bendable holding leaves integrally on both sides of the continuous plastic connecting sheet and inserting the nail shanks into the respective holding leaves for the connecting purpose. These types of connected nails are employed in different ways depending on the jobsite, and not only nailing machines capable of using both types of connected nails but also those adapted for alternately using both types of them have already been developed.
FIG. 6 shows the nail ejecting portion of a nailing machine for use in both types mentioned above. In a nose portion 20 provided in the lower portion of a nailing machine body, a nail ejecting opening 22 is formed for slidably guiding a driver 21 driven by a cylinder piston mechanism disposed within the body. An opening for introducing the front nail out of the connected nails in the nail ejecting opening 22 is formed in the nail ejecting opening 22. As shown in FIGS. 7(a) and 7(b), a nail feeding passage 25 is formed between a fixed guide wall 23 that is continuous to one side edge of the opening and used to guide the connected nails up to the nail ejecting opening 22 and a door member 24 that is openable with respect to the nose portion 20 and supported opposite to the fixed guide wall 23. A pressing plate 26 resiliently urged toward the fixed guide wall 23 is placed for the door member 24 whereby to maintain the space of the passage 25 for feeding wire-connected nails A and also to press nails B connected by a plastic sheet against the fixed guide wall 23. The nail feeding passage 25 is disposed on the line prolonged from the center line of the nail ejecting opening 22 so as to arrange each of the connected nails in the center of the nail ejecting opening 22.
When the front nail is hammered by the driver 21 in a case where the wire-connected nails A are used, a connecting wire 30 between the front nail 31 and the second nail 32 is cut, and the front nail 31 is hammered out of the nail ejecting opening 22 as the connected condition is removed. At this time, a cutoff piece 30a of the connecting wire 30 is formed on the front side of the shank of the second nail 32. Since the cutoff piece 30a is usually formed in the direction of the tip of the nail (downward) as shown in FIG. 6, it is hardly allowed to penetrate into a workpiece along the shank of the hammered nail. For this reason, the tip of the cutoff piece 30a comes into contact with the surface of the workpiece when the nail is hammered into the workpiece, and the cutoff piece 30a may be curved and separated from the wire-welded portion of the shank of the nail. This is dangerous because the cutoff pieces 30a may possibly fly in all directions.
In order to prevent the cut-pieces 30a from flying in all directions, depressions 27 for containing the front portions of the cutoff pieces 30a of the wire 30 are formed in the nail ejecting opening 22 of the nose portion 20 as shown in FIG. 6, so that each cutoff piece 30a attached to the shank of the hammered nail is formed upward. Since the tip of the cutoff piece 30a of the wire is received by the depression 27 when the nail is sent to the nose portion 20, the cutoff piece 30a is mated with the depression 27. Then the cutoff piece 30a is moved together with the shank portion of the nail when the nail is hammered out. Therefore, the cutoff piece 30a is directed upward and prevented from jumping up and down.
However, the depressions 27 for containing the front portions of the cutoff pieces 30a of the wire 30 are formed on the front side of the nail ejecting opening 22 of the nose portion 20 in the conventional art. Therefore, the tip of the cutoff piece 30a of the wire 30 may not be contained in the depression 27. This may happen in a case where the length of the cutoff piece 30a formed in front of the shank of the nail is short when connected nails have narrow connecting intervals or where the form of the cutoff piece 30a of the wire 30 becomes unstable. With respect to a special nailing machine for wire-connected nails A, the following technique has already been proposed as shown in FIG. 7(a): the depressions 27 formed in the nail ejecting opening 22 are formed in the side of the direction of supply to ensure that the cutoff pieces 30a are mated with the depressions 27 by eliminating the nonconformity stated above; moreover, the nails are supplied by shifting (offsetting) the nail feeding position in the direction in which the depressions 27 are formed to ensure that the cutoff pieces 30a are prevented from flying in all directions by allowing even the short cutoff pieces 30a to be contained in the depressions 27.
However, the introduction of the above technique into a nailing machine for use in both types results in placing a connecting sheet leaf 29 of the nail B connected by the plastic sheet closer to the center of the nail ejecting opening 22. Accordingly, the shoulder portion 29a of the connecting sheet leaf 29 is hammered by the driver 21 when the nail 31 is hammered as shown in FIG. 8. Consequently, the nail ejecting opening 22 may be clogged with the nail because the connecting sheet leaf 29 is crushed, and the supply of the nails B connected by the plastic sheet may also be impeded by the hammering trouble.
An object of the present invention is to provide a feeding mechanism for connected nails in a nailing machine for simultaneous use in hammering wire-connected nails A and nails B connected by a plastic sheet, wherein cutoff pieces of a wire can be effectively prevented from flying in all directions and wherein nails connected by the plastic sheet can also be supplied and hammered into a workpiece without impediments.
In order to solve the foregoing problems, there is provided a feeding mechanism for connected nails in a nailing machine capable of feeding not only wire-connected nails prepared by fusion-bonding a metal wire to the nail shanks but also nails connected by a long plastic sheet into the nail ejecting opening of a nose portion. The nails connected by the plastic sheet are prepared by inserting the nail shanks into the respective holding leaves formed along the extended direction of the plastic sheet. The wire-connected nail is supplied by offsetting the nail shank toward the wire-bonded portion of the wire-connected nail with respect to the center of the nail ejecting opening, and depressions for containing cutoff pieces of the wire-connected nails are formed in the offset side of the nail shank in the nail ejecting opening. A discharging opening for sheet leaves of the nails connected by the plastic sheet is offset so that the front end of a driver is prevented from hammering the connecting sheet leaf of the nail connected by the plastic sheet by guiding the connecting sheet leaf in a direction opposite to the direction of offsetting the shank of the wire-connected nail.